The present technology relates generally to the field of electrochromic devices. The variability in color and light transmittance of electrochromic materials with applied voltage has allowed the production of mirrors with variable reflectance and windows with variable light transmission. It is desirable in electrochromic devices to maintain a uniform appearance, such as a substantially uniform color, light transmittance, or reflectance across the device. Variations in the voltage applied to the electrochromic material in an electrochromic device may produce variations in the response of the electrochromic material, and thereby produce variations in the appearance of the electrochromic device.
The susceptibility of electrochromic devices to undesirable voltage variations may be a function of the current load of the electrochromic material. For example, a current load of the electrochromic material may increase as the area of the electrochromic device increases, the cell spacing of the electrochromic device decreases, or the concentration of the electrochromic dyes increases. An increased current load of the electrochromic device may produce an undesired voltage drop across the electrochromic device. The voltage drop produces a non-uniform response of the electrochromic material and a non-uniform appearance of the electrochromic device. Efforts have been made to reduce the voltage drop across an electrochromic device by increasing the conductivity of the electrodes providing the voltage to the electrochromic material. However, as the current load of the electrochromic materials continues to increase the conductivity of the electrodes cannot be increased sufficiently to fully prevent undesired voltage variations.